1. Field of the Invention
This invention relates to electric water heaters, and more particularly to diathermal water heaters that use electrical oscillations to rapidly heat water and like fluids to high temperatures.
2. Description of the Related Art Including Information Disclosed Under 37 C.F.R. .sctn..sctn. 1.97-1.98
Domestic and industrial water heating provides several useful advantages over the use of water at room temperature. With increased temperature, the cleaning and soluble capacity of water greatly increases and enhances the uses to which such heated water is put. In the home, hot water is used in cooking, bathing and cleaning. In the factory, hot water, wet steam and dry steam all have their appropriate uses under the specific conditions arising in industry.
The controlled heating of water has progressed significantly since the times water was boiled in a metal container over an open fire. In the home, electric and/or gas heaters are used to bring thirty to fifty gallons of water to high temperatures. Once heated, the water tank is maintained at the desired temperature by thermostatic control. Heat is dissipated from such heaters by radiation and by the introduction of cool water into the tank to replenish the hot water used in the home. Such electric water heaters generally use resistive elements while such gas heaters generally use burning gas to generate heat which is conducted from a firebox to the water tank.
Industrially, large boilers may also be heated in generally the same manner as is accomplished in the home. Large tanks of water are heated in boilers to provide hot water. In addition to electricity and gas, coal, oil, or other combustible substances may be used to provide heat in a firebox that is conducted to the water in the boiler.
An alternative method exists by which water may be heated. In the previously described methods, heat was provided in a form that was then conducted to the water in the tank or boiler. It is possible to directly heat water by the direct application of an electric current that runs through the water to be heated. In running electric current through the water, the water acts as a resistive element that is subject to resistive heating. The water through which the electric current is run is resistively-heated and any water surrounding such resistively-heated water is also heated by radiation and conduction from the resistively-heated water.
Drawbacks exist in these prior methods of heating water. Primarily, the electric, gas and related water heaters used in the home and factory must continually maintain the temperature of the water in the tank at a pre-selected level and in an amount that can quickly supply the demands for hot water. In maintaining a substantial or large reservoir of hot water, structures must be physically and mechanically provided that can occupy a great deal of space and that require significant expense to construct and maintain. Furthermore, beyond the plumbing necessary for delivery of cold water, an entirely separate and parallel plumbing system must be provided to deliver hot water from the reservoir to the place where it is required or desired. Beyond the additional structures required for hot water plumbing, radiative losses of heat from the hot water occurs as it is delivered from the reservoir to the point of demand. These radiative losses decrease the effectiveness of the hot water as it becomes cooler the farther it travels through its pipes. Insulating hot water pipes requires additional construction and maintenance.
Additionally, in attaining and maintaining the desired temperature of water in the hot water reservoir, energy must be expended to first attain the desired reservoir temperature and then additional energy must also be expended to maintain the water at that temperature. Although no demands may be placed that deplete the reservoir of heated water, the reservoir will always lose some heat which must be replenished by the addition of more energy in the form of heat.
A further drawback to heated reservoir systems occurs with the time required to heat a recently filled or replenished reservoir. Water has a significant heat capacity allowing it to absorb a significant amount of heat before its temperature rises. When a reservoir's temperature drops significantly below the preset temperature, the time it takes the energy source to heat the water back up to the desired temperature depends upon the heat source, the temperature of the water, and the size of the reservoir. As any person caught in the middle of taking a shower can confirm, the time it takes for a hot water heater to re-attain the selected temperature is usually too long and is rarely welcomed.
Drawbacks in those heaters that run current directly through the water to be heated also exist. Whenever water and electricity are mixed, stringent safeguards need to be provided in order to ensure that the electricity does not escape from its intended confines. Property damage and personal injury can arise should a short circuit occur or should the electricity escape from its intended paths. Furthermore, to control the performance of electrical current water heaters, the depth to which the electrodes are immersed in water has commonly been the preferred method of controlling the transmission of electricity through the water. This is a mechanical process with the inherent drawback that mechanical processes are generally much slower that electrical or electronic ones. A malfunction in the heater could quickly go awry causing damage or injury before the electrodes used to conduct the electricity through the water could be removed from the water.
It can be seen that there are significant advantages to providing a water heater that overcomes these drawback in previous water heaters. Further advantages may also be realized by providing a water heater that is sufficiently compact, energetic and efficient so that it can be located immediately adjacent to the point at which hot water, wet steam or dry steam may be required.